E. Semimembranosus has a broad tendon of origin passing deep to other hamstring muscles.

Explanation

(T, T, T, F, T)

You can find hamstring muscles in the posterior compartment of the thigh. The hamstring muscles are,

Semimembranosus

Semitendinosus

Biceps femoris

First two sentences are about the attachments of the hamstring muscles. All hamstring muscles arise from the ischial tuberosity and inserted into the tibia or fibula. So, both choices are true.

Attachments of hamstring muscles

If you know what is flexion of knee joint and extension of hip joint you know the answer for third choice. Understanding the flexion of knee joint is very easy. The movements of the hip joint are given below.

Movements of hip joint

Then if you can workout, hamstring muscles should flex the knee joint and extend the hip joint. So, 3rd choice is correct. For your knowledge, when knee semiflexed biceps femoris is a lateral rotator, while semimembranosus and semitendinosus are medial rotators of the leg.

It’s true that the hamstrings are innervated by tibial component of the sciatic nerve. But, short head of biceps femoris is supplied by common peroneal component of the sciatic nerve. So, fourth sentence is incorrect.

Fifth sentence is true. Semimembranosus has a broad tendon of origin lying deep to the other hamstring muscles. Look at the first two pictures above in the explanation!

2. Sciatic nerve

A. Is formed by the ventral and dorsal divisions of sacral ventral rami

B. Emerges from the pelvis through the lesser sciatic foramen

C. It divides at a constant level

D. When the nerve is completely damaged plantar flexion is diminished

E. Is related to the upper lateral quadrant of gluteal region

Explanation

(T, F, T, T, F)

Sciatic nerve is formed by dorsal and ventral divisions of anterior rami of L4, L5, S1, S2 and S3 spinal nerves.

Nerves emerging from various foramina of pelvis are given below in the picture. Sciatic nerve emerges through greater sciatic foramen.

Sciatic nerve divides into tibial and common peroneal nerves at the upper angle of the popliteal fossa.

Plantar flexion is done by muscles of the posterior compartment of the leg and it is supplied by the sciatic nerve. Nerve supply of lover limb muscles is illustrated in the following image.

Sciatic nerve does not related to the upper lateral quadrant of the gluteal region. That’s why intramuscular injection is administered to that area of the buttock.

3. Gluteus maximus

A. Has an origin from the sacrotuberous ligament.

B. Covers the gluteus medius completely

C. Is supplied by the inferior gluteal nerve from its deep surface

D. The main part of the muscle is inserted in to the gluteal tuberosity

E. Tendelenberg test is positive when the normal side is raised

Explanation

(T, F, T, F, F)

There are three gluteal muscles in the buttock.

Gluteus maximus

Gluteus medius

Gluteus minimus

Refer some text book to read about the attachments of the gluteal muscles. You will see that gluteaus medius has an origin from the sacrotuberous ligament.

Only the posterior third of gluteus medius is covered by gluteus maximus.

Gluteus maximus is supplied by posterior gluteal nerve.

Only the deep half of its lower half is inserted into the gluteal tuberosity. Rest three-quarter is inserted into the iliotibial tract.

Trendelenburg test is done to check the action of abductor muscles of the thigh; gluteus medius and gluteus minimus. We tell the patient to stand on one limb. When the patient stand on the affected limb the normal side severly drops over the swing limb.

4. Regarding joints of lower limb

A. Main abductors of hip joint are supplied by superior gluteal nerve

B. Tensor fascia lata stabilises the knee joint in the extended position

C. Acetabulum has both articular and non articular surfaces

D. Inversion and eversion both take place at ankle joint

E. Tendon of popliteus is intracapsular

Explanation

(T, F, T, T, F)

Hip joint is abducted by two muscles; gluteus medius and gluteus minimus. It is assisted by tensor fascia lata and sartorius. Both gluteus medius and minimus are supplied by superior gluteal nerve.

Muscles acting on hip joint

Tensor fascia lata is a thin sheet of muscle arising from external lip of iliac crest and inserts into iliotibial tract. It assists gluteal muscles in various positions, but has nothing to do with knee joint.

Tensor fascia latae

No need to explain C and D statements. Too easy! Both are true.

Popliteus is a muscle attached to the triangular area of the posterior surface of tibia above the soleal line and inserts into the lateral surface of the lateral condyle of femur through a cord like tendon. This tendon is intracapsular, but not the muscle.

Foot drop occurs due to paralysis of extensor muscles in the leg which is supplied by deep branch of common peroneal nerve. Tibial nerve supplies flexor muscles of the leg.

Both B anc C statements are about nerve supply of lower limb muscles. You should remember them. I believe that the best way is to make charts and tables.

Pectineus is supplied by the femoral nerve, occasionally it receives a twig from obturator nerve.

Adductor hallucis is a muscle in the foot and is supplied by deep branch of lateral plantar nerve.

Knee joint is supplied from,

femoral nerve through its branches vastus medialis, intermedius and lateralis,

sciatic nerve by the genicular branches of its tibial and common peroneal components,

obturator nerve by the twig from its posterior division.

Hip joint is supplied from,

femoral nerve via the nerve to rectus femoris,

obturator nerve directly from its anterior division,

the nerve to quadratus femoris,

articular twigs from the sciatic nerve.

Final statement is easy, but you need a mnemonic or a clear picture memory to answer this. Actually, saphenous nerve crosses femoral artery from lateral to medial side in the adductor canal. LSM is a mnemonic to remember this. Lateral-Saphenous-Medial. Below is a picture of the incident.

A prime mover is the muscle whose contraction causes majorly the desired movement. So prime mover of elbow flexion is biceps. What is the prime mover of elbow extension?

Supraspinatus causes abductions of the shoulder joint.

Flexors of the shoulder joint are,

Clavicular head of pectoralis major

Anterior fibres of biceps

They are assisted by coracobrachialis and short head of biceps

Synergists are muscles which prevent unwanted movements and stabilise the joints.

Antagonists do the opposite of prime movers. So, triceps is an antagonist of elbow flexion.

2. Regarding bio mechanics

A. Most joints in the body has mechanical advantage of more than 1

B. Atlanto-occipital joint is an example for 1st class lever

C. Deltoid muscle is an prime mover for abduction at the shoulder joint

D. Pectoralis minor is a fixator of shoulder joint

E. Centre of gravity is outside the pelvis

Explanation

(F, T, T, F, F)

Mechanical advantage is calculated as length from fulcrum to effort divided by length from fulcrum to load. (Look at the picture). On that basis the mechanical advantage of most of the joints in the body is less than 1.

There are joints in the body which act as first, second or third class levers.

Above picture shows an example for a third class lever. There effort is between load and fulcrum.

Below picture shows a second class lever. Load is between fulcrum and effort.

Here is a first class lever. Fulcrum (pivot) is between load and effort.

There is a mnemonic to remember this; FLE 321 (Did you get it?)

So, atlanto-occipital joint is a first class lever.

Deltoid is the principal abductor of the shoulder joint.

Refer the attachments of pectoralis minor. It has no business with shoulder joint.

The centre of gravity should be within the pelvis. Otherwise we’ll have to fall every time.

3. In relation to movements of muscle groups

A. Biceps brachii is the prime mover in elbow flexion

B. Synergistic muscle stabilise joints

C. Pectoralis major is a fixator in shoulder joint movement

D. Triceps is an antagonist during extension

E. Supraspinatus is a prime mover during shoulder abduction

Explanation

(T, T, T, F, T)

First two sentences have been explained in previous questions.

Fixator is a muscle which fixes a joint allowing it to complete another movement. Regarding pectoralis major, its actions are as follows.

Adduction (by sternocostal fibres mainly)

Medical rotation

Flexion is assisted by clavicular head.

Fixes the shoulder joint in abduction

Fourth and fifth sentences have also been explained before.

4. In the upper limb, the

A. Brachial arterial pulse can be felt over the medial aspect of the humeral shaft

Brachial artery is the continuation of the axillary artery. It runs just beneath the deep fascia in the arm anteromedially. So, brachial arterial pulse can be felt in the anteromedial aspect of the arm.

Tendon and the free edge of the bicipital aponeurosis is palpable in the anterior cubital fossa.

Head of the radius is subcutaneous. So, it is palpable in the depression just behind the lateral aspect of the extended elbow. You can also feel the movements, pronation and suination.

Ulnar artery disappears in the cubital fossa and lies deep within the forearm and form the superficial palmer arch in the hand. Ulnar arterial pulse can be felt just lateral to the tendon of flexor carpi ulnaris. NOT medial!

5. The deltoid muscle

A. Is multipennate.

B. Is attached to the surgical neck of the humerus

C. Can be paralysed following a fracture of the surgical neck of the humerus

D. Is paralysed following a complete tear of the upper trunk of the brachial plexus

E. Is supplied by the posterior cord of the brachial plexus

Explanation

(T, F, T, T, T)

Deltoid is the muscle which form the bulk of the shoulder. It has three parts.

Anterior fibres

Middle fibres

Posterior fibres, among these middle section is multipennate.

You should refer the attachments of deltoid. It origins from lateral one-third of clavicle, lateral border of acromion and scapular spine and attaches to the deltoid tuberosity.

The last three sentences are interesting. You have to know about the brachial plexus and the nerve supply of deltoid. Deltoid is supplied by the axillary nerve. It runs around the surgical neck of humerus. So, a fracture there can damage the axillary nerve paralysing deltoid.

Now the brachial plexus. There are Roots, Trucks, Divisions, Cords and Branches arising from them. Rugby Team Drinks Cold Beers.

B. True – In the intercostal space the nerve lies in the subcostal groove between the internal intercostal muscle and innermost intercostal muscles. Can you identify the muscles in the above picture?

C. True – The collateral branch arising near the angle of the rib supplies the muscles of that space. It also supplies the parietal pleura and the parietal peritoneum in the case of the lower nerves.

D. False – In the costal groove the nerve lies below the intercostal vessels. The order from above downwards is vein, artery and nerve. VAN from above downwards.

The VAN

E. True – Look at the picture below!

2. Regarding intercostal nerves

A. The anterior primary ramus of the twelfth thoracic nerve is the subcostal nerve
B. The 7th intercostal nerve is a typical spinal nerve
C. They lie in the subcostal groove
D. The 4th intercostal nerve supplies only the thoracic wall
E. The 2nd has a supply to the skin of the axilla

Explanation

A. True – This is mere knowledge. Subcostal nerve?

B. False – The 3rd to 6th intercostal nerves supply only the thoracic wall and are called typical nerves. The 7th to 11th nerves supply the abdominal wall in addition to the intercostal spaces

C. True – You saw the VAN!

D. True – 4th intercostal nerve is a typical intercostal nerve

E. True – The lateral cutaneous branch of the 2nd intercostal nerve crosses the axilla to the medial side of the arm as the intercostobrachial nerve and supplies the skin of the axilla . Not infrequently the lateral cutaneous nerve of the 3rd intercostal nerve also supplies the skin of the axilla.

Can you see the 2nd intercostal nerve?

3. Regarding intercostal arteries

A. All posterior intercostal arteries arise from the descending aorta
B. They lie superior to the vein and nerve in the costal groove
C. All anterior intercostal arteries arise from the internal thoracic artery
D. Posterior intercostal arteries supply the spinal cord
E. The right third posterior intercostal artery gives off the right bronchial artery

Explanation

A. False – The 3rd – 11th arteries arise from the descending aorta. The 1st and 2nd arise from the superior intercostal artery which is a branch of the costocervical trunk.

Look where the 1st and 2nd posterior intercostal arteries come from…

B. False – VAN again?

C. False – The upper six arise from the internal thoracic artery and the 7th to 9th arise from the musculophrenic artery.

D. True – The dorsal branch which supplies the muscles and skin at the back gives off a spinal branch which supplies the spinal cord and vertebrae.

E. True – You can just see the right bronchial artery which supplies the right bronchi in the picture below. It is arises from the 3rd posterior intercostal artery.

4. External intercostal muscle

A. is innervated by the posterior ramus of the thoracic spinal nerve
B. is derived from the paraxial mesoderm
C. extends as far forwards as the costochondral junction
D. has an attachment to the neck of the respective rib
E. has fibres directed downwards and backwards

Explanation

A. False – The intercostal muscles are innervated by the corresponding intercostal nerve. The intercostal nerves are the anterior rami of first 11 thoracic spinal nerves. The anterior ramus of the twelfth thoracic nerve lies in the abdomen and runs forward in the abdominal wall as the subcostal nerve

B. True – Do you remember the paraxial mesoderm? (Paraxial means just lateral to the central axis)

Although the ribs develop from sclerotome the intercostal muscles develop from the somatic mesoderm. (body wall muscles)

C. True – The muscle extends as far forwards as the costochondral junction and continues as the anterior intercostal membrane.

Anterior/External intercostal membrane

D. False – It is attached to the tubercle of the rib

E. False – The fibres of the external intercostal muscle are directed downwards and forwards. The fibres of the internal intercostal muscle are directed downwards and backwards.

Memory tip:

To remember this, when you put your hands in the pocket your fingers lie in the direction of the external intercostal muscle fibres. When you grab your chest by crossed hands your fingers lie in the direction of internal intercostal muscle fibers.

5. Internal thoracic artery

A. arises from the first part of the subclavian artery
B. supplies the upper six intercostal spaces
C. supplies the thymus
D. gives off the superior epigastric artery
E. terminates in the 5th intercostal space

Explanation

A. True – It is the second branch that arises from the inferior aspect of the first part of the subclavian artery. Try to workout the arteries arising from 1st, 2nd and 3rd parts of the subclavian artery by using the picture below.

B. True – It gives off two anterior intercostals to each of the upper six intercostal spaces.

C. True – It supplies the thymus via mediastinal branches.

Blood supply of thymus gland

D. True – The artery terminates in the 6th intercostal space by dividing into superior epigastric and musculophrenic artery. Below picture shows the branches of the internal thoracic artery.